The effects of differences in age on some of the long-term effects of chronic neuroleptic drugs will be investigated using behavioral, biochemical and morphological measures. Young, adult and older age rats will be administered neuroleptic drugs for 6-7 weeks. Behavioral assessments will be carried out before, during, and after termination of chronic neuroleptic medication. These will include measures of locomotor activity, stereotyped behavior or other abnormal movements, and responses to a conditioned avoidance task; animals will be tested both with and without prior administration of the DA agonist drug apomorphine. Biochemical tests will concentrate on assessment of HVA response to dopamine agonists and studies of synaptosomal dopamine uptake. Since the human syndrome of tardive dyskinesia, one clinical syndrome believed to be associated with long-term neuroleptic treatment in man, is more prevalent in older age populations, this research will investigate whether older animals will show more severe or prolonged evidence of dopaminergic supersensitivity or other defects after chronic neuroleptic administration.